Frankly I wouldn't even think about trying to buy a used or even "new old stock" B&O original cartridge as they are now so old that suspension decay is a more than likely problem and you will have no guarantee of the condition or longevity. A far better bet would be a brand new soundsmith mmc20E or even better mmc20EN item which come with full warranty and are better than the B&O originals. Not quite as refined as the original B&O ones though I have to admit.
Several Beoworld members (including myself) have bought from here and everyone agrees they are excellent.
Chris.
The use of metaphors should be avoided like the plague. They're like a red rag to a bull to me.